A cost-consequence model of using the 21-gene assay to identify patients with early-stage node-positive breast cancer who benefit from adjuvant chemotherapy in the Netherlands

BACKGROUND

Patients with early-stage hormone receptor positive, human epidermal growth factor receptor-2 (HER2) negative invasive breast cancer with 1-3 positive lymph nodes (N1) often undergo surgical excisions followed by adjuvant chemotherapy (ACT). Many patients have no benefit from ACT and receive unnecessary, costly treatment often associated with short- and long-term adverse events (AEs). Gene expression profiling (GEP) assays, such as the 21-gene assay (i.e. the Oncotype DX assay), can identify patients at higher risk for recurrence who may benefit from ACT. However, the budgetary consequence of using the Oncotype DX assay versus no GEP testing in the Netherlands is unknown. Our study therefore assessed it using a cost-consequence model.

METHODS

A validated model was used to create the N1 model. The model compared the costs and consequences of using the Oncotype DX assay versus no GEP testing and MammaPrint, and subsequent ACT use with corresponding costs for chemotherapy, treatment of AEs, productivity losses, GEP testing, and treatment of recurrences, according to the Oncotype DX results. The model time horizon was 5 years.

RESULTS

Costs for the total population amounted to €8.0 million (M), €16.2 M, and €9.5 M, and cost per patient amounted to €13,540, €27,455, and €16,154 for using the Oncotype DX assay, no GEP testing, and MammaPrint, respectively. Total cost savings of using the Oncotype DX assay amounted to €8.2 M versus no GEP testing and €1.5 M versus MammaPrint. Using the Oncotype DX assay would result in fewer patients receiving ACT and thus fewer AEs, sick days, and hospitalizations, leading to overall cost savings compared with no GEP testing and MammaPrint.

CONCLUSIONS

Implementing Oncotype DX testing in this population can prevent unnecessary overtreatment, reducing clinical and economic burden on the patient and Dutch healthcare system.

Loss of skeletal muscle index and survival in patients with metastatic colorectal cancer: Secondary analysis of the phase 3 CAIRO3 trial

Background

Low skeletal muscle index (SMI) in metastatic colorectal cancer (mCRC) patients is associated with poor outcomes. The prognostic impact of SMI changes during consecutive palliative systemic treatments is unknown.

Methods

This is a retrospective analysis of the phase 3 CAIRO3 study. The CAIRO3 study randomized 557 patients between maintenance capecitabine + bevacizumab (CAP‐B) or observation, after six cycles capecitabine + oxaliplatin + bevacizumab (CAPOX‐B). Upon first disease progression (PD1), CAPOX‐B was reintroduced until second progression (PD2). SMI was assessed by computed tomography (CT) (total 1355 scans). SMI and body mass index (BMI) changes were analyzed for three time‐periods; p1: during initial CAPOX‐B, p2: randomization to PD1, and p3: PD1 to PD2. The association between absolute and change in SMI and BMI (both per 1 standard deviation) during p1‐p3, with PD1, PD2, and survival was studied by Cox regression models.

Results

This analysis included 450 of the 557 patients randomized in the CAIRO3 study. Mean SMI decreased during p1: mean −0.6 SMI units [95% CI −1.07;‐0.26] and p3: −2.2 units [−2.7;‐1.8], whereas during p2, SMI increased + 1.2 units [0.8‐1.6]. BMI changes did not reflect changes in SMI. SMI loss during p2 and p3 was significantly associated with shorter survival (HR 1.19 [1.09‐1.35]; 1.54 [1.31‐1.79], respectively). Sarcopenia at PD1 was significantly associated with early PD2 (HR 1.40 [1.10‐1.70]). BMI loss independent of SMI loss was only associated with shorter overall survival during p3 (HR 1.35 [1.14‐1.63]).

Conclusions

In mCRC patients, SMI loss during palliative systemic treatment was related with early disease progression and reduced survival. BMI did not reflect changes in SMI and could not identify patients at risk of poor outcome during early treatment lines.

Androgen receptor expression in circulating tumor cells of patients with metastatic breast cancer

The androgen receptor (AR) has potential clinical relevance in metastatic breast cancer (mBC) since it might be a treatment target and has been associated with endocrine resistance. A minimal-invasive way to determine AR expression on metastatic tumor cells is by characterization of circulating tumor cells (CTCs). Here, we assessed AR mRNA expression in CTCs (CTC-AR) and in matched primary tumor samples from mBC patients representing different breast cancer subtypes. In addition, we explored CTC-AR-status in relation to outcome on endocrine therapy. AR, and 92 AR or estrogen receptor (ER) related genes, were measured in CellSearch-enriched CTCs from 124 mBC patients and in 52 matched FFPE primary tissues using quantitative reverse-transcriptase PCR. AR in CTCs was considered positive if the expression was 1 standard deviation higher than the expression measured in 11 healthy blood donors. A total of 31% of the mBC patients had AR-positive (AR+) CTCs. 58% of the matched CTC and primary tumor samples were discordant with respect to AR status, observing both switches from AR+ to AR-negative (AR-) and vice versa. There was no statistically significant difference in progression-free survival for patients treated with ER-targeting drugs and CTC-AR-status (13 AR+/ 37 AR- cases, p = 0.28). Thus, AR can be determined in RNA isolated from CTCs, with in our set 31% AR-positive samples. Given the discordance between AR status in CTC samples and corresponding primary tumors, determination of AR expression in CTCs might be a promising tool to select mBC patients for AR inhibiting agents.

An Optimized Workflow to Evaluate Estrogen Receptor Gene Mutations in Small Amounts of Cell-Free DNA

The detection of mutated genes in cell-free DNA (cfDNA) in plasma has emerged as an important minimally invasive way to obtain detailed information regarding tumor biology. Reliable determination of circulating tumor-derived DNA, often present at a low quantity amidst an excess of normal DNA in plasma, would be of added value for screening and monitoring of cancer patients and for hypothesis-generating studies in valuable retrospective cohorts. Our aim was to establish a workflow to simultaneously assess four hotspot estrogen receptor mutations (mESR1) in cfDNA isolated from only 200 μL of plasma by means of uniplex or multiplex pre-amplification combined with digital PCR. This workflow was then applied in metastatic breast cancer (MBC) patients receiving systemic therapies for MBC. In accordance with previous studies, estrogen receptor mutations were more frequently detected in endocrine-treated MBC patients at progressive disease [34.1% (15/44)] than before the start of endocrine therapy [3.9% (2/51); P = 0.001]. For a subset of samples, results were compared with analysis of these mutations by Oncomine-targeted next-generation sequencing, which, although requiring a higher cfDNA input, yielded concordant results. The data establish development and validation of a digital PCR workflow for the simultaneous detection of several tumor-derived mutations in minute amounts of cfDNA and show the potential of this workflow for use on archived volume-limited blood samples.

Estrogen receptor mutations and splice variants determined in liquid biopsies from metastatic breast cancer patients

Mutations and splice variants in the estrogen receptor (ER) gene, ESR1, may yield endocrine resistance in metastatic breast cancer (MBC) patients. These putative endocrine resistance markers are likely to emerge during treatment, and therefore, its detection in liquid biopsies, such as circulating tumor cells (CTCs) and cell‐free DNA (cfDNA), is of great interest. This research aimed to determine whether ESR1 mutations and splice variants occur more frequently in CTCs of MBC patients progressing on endocrine treatment. In addition, the presence of ESR1 mutations was evaluated in matched cfDNA and compared to CTCs. CellSearch‐enriched CTC fractions (≥5/7.5 mL) of two MBC cohorts were evaluated, namely (a) patients starting first‐line endocrine therapy (n = 43, baseline cohort) and (b) patients progressing on any line of endocrine therapy (n = 40, progressing cohort). ESR1 hotspot mutations (D538G and Y537S/N/C) were evaluated in CTC‐enriched DNA using digital PCR and compared with matched cfDNA (n = 18 baseline cohort; n = 26 progressing cohort). Expression of ESR1 full‐length and 4 of its splice variants (∆5, ∆7, 36 kDa, and 46 kDa) was evaluated in CTC‐enriched mRNA. It was observed that in the CTCs, the ESR1 mutations were not enriched in the progressing cohort (8%), when compared with the baseline cohort (5%) (P = 0.66). In the cfDNA, however, ESR1 mutations were more prevalent in the progressing cohort (42%) than in the baseline cohort (11%) (P = 0.04). Three of the same mutations were observed in both CTCs and cfDNA, 1 mutation in CTCs only, and 11 in cfDNA only. Only the ∆5 ESR1 splice variant was CTC‐specific expressed, but was not enriched in the progressing cohort. In conclusion, sensitivity for detecting ESR1 mutations in CTC‐enriched fractions was lower than for cfDNA. ESR1 mutations detected in cfDNA, rarely present at the start of first‐line endocrine therapy, were enriched at progression, strongly suggesting a role in conferring endocrine resistance in MBC.

Estrogen receptor mutations and splice variants determined in liquid biopsies from metastatic breast cancer patients

Mutations and splice variants in the estrogen receptor (ER) gene, ESR1, may yield endocrine resistance in metastatic breast cancer (MBC) patients. These putative endocrine resistance markers are likely to emerge during treatment, and therefore, its detection in liquid biopsies, such as circulating tumor cells (CTCs) and cell-free DNA (cfDNA), is of great interest. This research aimed to determine whether ESR1 mutations and splice variants occur more frequently in CTCs of MBC patients progressing on endocrine treatment. In addition, the presence of ESR1 mutations was evaluated in matched cfDNA and compared to CTCs. CellSearch-enriched CTC fractions (≥5/7.5 mL) of two MBC cohorts were evaluated, namely (a) patients starting first-line endocrine therapy (n = 43, baseline cohort) and (b) patients progressing on any line of endocrine therapy (n = 40, progressing cohort). ESR1 hotspot mutations (D538G and Y537S/N/C) were evaluated in CTC-enriched DNA using digital PCR and compared with matched cfDNA (n = 18 baseline cohort; n = 26 progressing cohort). Expression of ESR1 full-length and 4 of its splice variants (∆5, ∆7, 36 kDa, and 46 kDa) was evaluated in CTC-enriched mRNA. It was observed that in the CTCs, the ESR1 mutations were not enriched in the progressing cohort (8%), when compared with the baseline cohort (5%) (P = 0.66). In the cfDNA, however, ESR1 mutations were more prevalent in the progressing cohort (42%) than in the baseline cohort (11%) (P = 0.04). Three of the same mutations were observed in both CTCs and cfDNA, 1 mutation in CTCs only, and 11 in cfDNA only. Only the ∆5 ESR1 splice variant was CTC-specific expressed, but was not enriched in the progressing cohort. In conclusion, sensitivity for detecting ESR1 mutations in CTC-enriched fractions was lower than for cfDNA. ESR1 mutations detected in cfDNA, rarely present at the start of first-line endocrine therapy, were enriched at progression, strongly suggesting a role in conferring endocrine resistance in MBC.

Impact of skeletal muscle index (SMI) loss during palliative systemic treatment (Tx) on time to progression and overall survival (OS) in metastatic colorectal cancer (mCRC) patients

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Background: Evidence for a strong link between skeletal muscle depletion and poor outcomes in mCRC is growing. However, the impact of SMI changes over time on progression and OS during palliative systemic Tx is not known. The CAIRO3 study (Simkens et al. Lancet 2015) randomized 556 mCRC patients after 6 cycles capecitabine+oxaliplatin+bevacizumab (CAPOX-B) to maintenance CAP-B Tx (Main) vs. observation (Obs). Upon 1st disease progression (PD1), CAPOX-B or other treatment was reintroduced until 2nddisease progression (PD2). This is the first analysis using scan data of multiple time-points to investigate SMI changes during palliative systemic treatment Tx and its association with survival. Methods: 1227 CT-scans of a random selection of 416 CAIRO3 patients (mean age 64±9 years, Main n = 206; Obs n = 210) were analyzed for SMI (skeletal muscle area at the L3 level in cm2/m2). Using mixed model analysis, SMI changes were analyzed for two intervals; interval 1: from randomization to PD1, and interval 2: from PD1 to PD2. Three Cox regression models were used to study the association between SMI loss and time to PD2 and death for interval 1, and time to death for interval 2. Main and Obs groups were combined in the analyses since the p-value for interaction was not significant. Hazard ratios (HR) were reported per 2 units change in SMI. Results: Median times from randomization to PD1, PD2 and death were 7.7, 13.5 and 24 months resp. During interval 1 (less intensive or no Tx) patients gained SMI on average (1.2 units; 95%CI 0.6-1.8), but 23% of patients still lost SMI. SMI loss was associated with shorter time to PD2 (HR 0.88; 0.81-0.98, p= .01), but not with shorter OS (HR 0.94; 0.86-1.02, p= .17). During interval 2 (more intensive Tx) average SMI loss was -2.2 units ( 1.5-2.8) and 63% of patients lost SMI. SMI loss was associated with shorter OS (HR 0.73; 0.62-0.86, p< .00). Conclusions: Loss of SMI was related to shorter time to progression during first line less intensive main Tx or obs and shorter overall survival during more intensive reinduction Tx. This large longitudinal study suggests that SMI preservation may be a therapeutic goal. Clinical trial information: NCT00442637.

Prognostic Impact of HER2 and ER Status of Circulating Tumor Cells in Metastatic Breast Cancer Patients with a HER2-Negative Primary Tumor

BACKGROUND

Preclinical and clinical studies have reported that human epidermal growth factor receptor 2 (HER2) overexpression yields resistance to endocrine therapies. Here the prevalence and prognostic impact of HER2-positive circulating tumor cells (CTCs) were investigated retrospectively in metastatic breast cancer (MBC) patients with a HER2-negative primary tumor receiving endocrine therapy. Additionally, the prevalence and prognostic significance of HER2-positive CTCs were explored in a chemotherapy cohort, as well as the prognostic impact of the estrogen receptor (ER) CTC status in both cohorts.

METHODS

Included were MBC patients with a HER2-negative primary tumor, with ≥1 detectable CTC, starting a new line of treatment. CTCs were enumerated using the CellSearch system, characterized for HER2 with the CellSearch anti-HER2 phenotyping reagent, and characterized for ER mRNA expression. Primary end point was progression-free rate after 6 months (PFR6months) of endocrine treatment in HER2-positive versus HER2-negative CTC patients.

RESULTS

HER2-positive CTCs were present in 29% of all patients. In the endocrine cohort (n=72), the PFR6months was 53% for HER2-positive versus 68% for HER2-negative CTC patients (P=.23). In the chemotherapy cohort (n=82), no prognostic value of HER2-positive CTCs on PFR6months was observed either. Discordances in ER status between the primary tumor and CTCs occurred in 25% of all patients but had no prognostic value in exploratory survival analyses.

CONCLUSION

Discordances regarding HER2 status and ER status between CTCs and the primary tumor occurred frequently but had no prognostic impact in our MBC patient cohorts.

An 8-gene mRNA expression profile in circulating tumor cells predicts response to aromatase inhibitors in metastatic breast cancer patients

Background

Molecular characterization of circulating tumor cells (CTC) is promising for personalized medicine. We aimed to identify a CTC gene expression profile predicting outcome to first-line aromatase inhibitors in metastatic breast cancer (MBC) patients. Methods: CTCs were isolated from 78 MBC patients before treatment start. mRNA expression levels of 96 genes were measured by quantitative reverse transcriptase polymerase chain reaction. After applying predefined exclusion criteria based on lack of sufficient RNA quality and/or quantity, the data from 45 patients were used to construct a gene expression profile to predict poor responding patients, defined as disease progression or death <9 months, by a leave-one-out cross validation.

Results

Of the 45 patients, 19 were clinically classified as poor responders. To identify them, the 75 % most variable genes were used to select genes differentially expressed between good and poor responders. An 8-gene CTC predictor was significantly associated with outcome (Hazard Ratio [HR] 4.40, 95 % Confidence Interval [CI]: 2.17–8.92, P < 0.001). This predictor identified poor responding patients with a sensitivity of 63 % and a positive predictive value of 75 %, while good responding patients were correctly predicted in 85 % of the cases. In multivariate Cox regression analysis, including CTC count at baseline, the 8-gene CTC predictor was the only factor independently associated with outcome (HR 4.59 [95 % CI: 2.11–9.56], P < 0.001). This 8-gene signature was not associated with outcome in a group of 71 MBC patients treated with systemic treatments other than AI.

Conclusions

An 8-gene CTC predictor was identified which discriminates good and poor outcome to first-line aromatase inhibitors in MBC patients. Although results need to be validated, this study underscores the potential of molecular characterization of CTCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2155-y) contains supplementary material, which is available to authorized users.

Maintenance treatment with capecitabine and bevacizumab in metastatic colorectal cancer (CAIRO3): a phase 3 randomised controlled trial of the Dutch Colorectal Cancer Group

BACKGROUND

The optimum duration of first-line treatment with chemotherapy in combination with bevacizumab in patients with metastatic colorectal cancer is unknown. The CAIRO3 study was designed to determine the efficacy of maintenance treatment with capecitabine plus bevacizumab versus observation.

METHODS

In this open-label, phase 3, randomised controlled trial, we recruited patients in 64 hospitals in the Netherlands. We included patients older than 18 years with previously untreated metastatic colorectal cancer, with stable disease or better after induction treatment with six 3-weekly cycles of capecitabine, oxaliplatin, and bevacizumab (CAPOX-B), WHO performance status of 0 or 1, and adequate bone marrow, liver, and renal function. Patients were randomly assigned (1:1) to either maintenance treatment with capecitabine and bevacizumab (maintenance group) or observation (observation group). Randomisation was done centrally by minimisation, with stratification according to previous adjuvant chemotherapy, response to induction treatment, WHO performance status, serum lactate dehydrogenase concentration, and treatment centre. Both patients and investigators were aware of treatment assignment. We assessed disease status every 9 weeks. On first progression (defined as PFS1), patients in both groups were to receive the induction regimen of CAPOX-B until second progression (PFS2), which was the study's primary endpoint. All endpoints were calculated from the time of randomisation. Analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00442637.

FINDINGS

Between May 30, 2007, and Oct 15, 2012, we randomly assigned 558 patients to either the maintenance group (n=279) or the observation group (n=279). Median follow-up was 48 months (IQR 36-57). The primary endpoint of median PFS2 was significantly improved in patients on maintenance treatment, and was 8·5 months in the observation group and 11·7 months in the maintenance group (HR 0·67, 95% CI 0·56-0·81, p<0·0001). This difference remained significant when any treatment after PFS1 was considered. Maintenance treatment was well tolerated, although the incidence of hand-foot syndrome was increased (64 [23%] patients with hand-foot skin reaction during maintenance). The global quality of life did not deteriorate during maintenance treatment and was clinically not different between treatment groups.

INTERPRETATION

Maintenance treatment with capecitabine plus bevacizumab after six cycles of CAPOX-B in patients with metastatic colorectal cancer is effective and does not compromise quality of life.

FUNDING

Dutch Colorectal Cancer Group (DCCG). The DCCG received financial support for the study from the Commissie Klinische Studies (CKS) of the Dutch Cancer Foundation (KWF), Roche, and Sanofi-Aventis.

Gene expression profiles of circulating tumor cells versus primary tumors in metastatic breast cancer

Before using circulating tumor cells (CTCs) as liquid biopsy, insight into molecular discrepancies between CTCs and primary tumors is essential. We characterized CellSearch-enriched CTCs from 62 metastatic breast cancer (MBC) patients with ≥5 CTCs starting first-line systemic treatment. Expression levels of 35 tumor-associated, CTC-specific genes, including ESR1, coding for the estrogen receptor (ER), were measured by reverse transcription quantitative polymerase chain reaction and correlated to corresponding primary tumors. In 30 patients (48%), gene expression profiles of 35 genes were discrepant between CTCs and the primary tumor, but this had no prognostic consequences. In 15 patients (24%), the expression of ER was discrepant. Patients with ER-negative primary tumors and ER-positive CTCs had a longer median TTS compared to those with concordantly ER-negative CTCs (8.5 versus 2.1 months, P = 0.05). From seven patients, an axillary lymph node metastasis was available. In two patients, the CTC profiles better resembled the lymph node metastasis than the primary tumor. Our findings suggest that molecular discordances between CTCs and primary tumors frequently occur, but that this bears no prognostic consequences. Alterations in ER-status between primary tumors and CTCs might have prognostic implications.

Neutrophil-guided dosing of anthracycline-cyclophosphamide-containing chemotherapy in patients with breast cancer: a feasibility study

The aim of this study was to investigate whether neutrophil-guided dose escalation of anthracycline-cyclophosphamide-containing chemotherapy (ACC) for breast cancer is feasible, in order to optimize outcome. Breast cancer patients planned for 3-weekly ACC were enrolled in this study. The first treatment cycle was administered in a standard BSA-adjusted dose. The absolute neutrophil count was measured at baseline and at day 8, 11 and 15 after administration of ACC. For patients with none or mild (CTC grade 0-2) neutropenia and no other dose-limiting toxicity, we performed a 10-25 % dose escalation of the second cycle with the opportunity to a further 10-25 % dose escalation of the third cycle. Thirty patients were treated in the adjuvant setting with either FE100C (n = 23) or AC (n = 4), or in the palliative setting with FAC (n = 3). Two out of 23 patients (9 %) treated with FEC did not develop grade 3-4 neutropenia after the first treatment cycle. Dose escalation was performed in these two patients (30 % in one and 15 % in the other patient). During dose escalation, there were no complications like febrile neutropenia. No patients treated with FAC or AC could be escalated, since all of them developed grade 3-4 neutropenia. We conclude that asymptomatic grade 3-4 neutropenia is likely to be achieved in the majority of patients with breast cancer treated with ACC according to presently advocated BSA-based dose levels. Escalation of currently advocated ACC doses without G-CSF, with a target of grade 3-4 neutropenia, is feasible, but only possible in a small proportion of patients. EudraCT 2010-020309-33.

mRNA expression profiles in circulating tumor cells (CTCs) of patients with metastatic breast cancer (MBC) treated with aromatase inhibitors (AI)

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Background: Enumeration of CTCs can be used to assess prognosis in MBC and to evaluate treatment response. Besides enumeration, molecular CTC characterization is a promising tool to develop a more personalized treatment approach. Here, we evaluated the association between mRNA expression of currently known CTC-specific genes and response to first-line AI in MBC patients with estrogen receptor (ER)+ primary tumors. Methods: CTCs were isolated and enumerated from blood of 25 MBC patients before first-line therapy with an AI. Fourteen patients received a non-steroidal AI (8 letrozole, 6 anastrozole) and 11 patients were treated with exemestane. mRNA expression levels of 96 genes were measured by quantitative RT-PCR as previously described (Sieuwerts et al. Clin Cancer Res. 17:3600-3618, 2011). Expression levels of these genes were studied for their association with time to progression (TTP) after start first-line AI. Results: Median TTP was 338 (range 14–1,239) days. Median baseline CTC count for the 25 patients was 14 (range 0–753). In this relatively small cohort, the clinically relevant cut-off level of ≥5 CTCs in association with TTP did not reach statistical significance (Hazard Ratio [HR] 4.76, 95% Confidence Interval [CI]: 0.59–38.22, P=0.14). For type of AI, when comparing steroidal with non-steroidal AI, the measures in Cox univariate regression analysis were HR 2.54 (95% CI: 0.67–9.64), P=0.17. A 10-gene CTC profile was constructed based on the Wald statistics of the contribution of the individual genes in univariate Cox regression analysis of TTP. To identify patients with good and poor outcome, the Wald corrected sum of the 10 genes was used to dichotomize the continuous 10-gene predictor (HR 12.87 [95% CI: 1.60–103.56], P=0.016). In multivariate analysis, corrected for the clinically relevant variables type of AI and CTC count, only the 10-gene CTC profile was an independent factor associated with TTP (HR 12.46 [95% CI: 1.29-120.08], P=0.029). Conclusions: A 10-gene CTC predictor was constructed which distinguishes good and poor outcome to first-line AI in MBC patients. This profile is currently being validated in an independent group of patients.

Maintenance treatment with capecitabine and bevacizumab versus observation after induction treatment with chemotherapy and bevacizumab in metastatic colorectal cancer (mCRC): The phase III CAIRO3 study of the Dutch Colorectal Cancer Group (DCCG)

3502

Background: The optimal duration of chemotherapy and bevacizumab in mCRC is not well established. The CAIRO3 study investigated the efficacy of maintenance treatment with capecitabine plus bevacizumab versus observation in mCRC pts not progressing during induction treatment with capecitabine, oxaliplatin and bevacizumab (CAPOX-B). Methods: Previously untreated mCRC pts, PS 0-1, with stable disease or better after 6 cycles of CAPOX-B, not eligible for metastasectomy and eligible for future treatment with oxaliplatin, were randomized between observation (arm A) or maintenance treatment with capecitabine 625 mg/m2 bid dailycontinuouslyand bevacizumab 7.5 mg/kg iv q 3 weeks (arm B). Upon first progression (PFS1), pts in both arms were treated with CAPOX-B until second progression (PFS2, primary endpoint). For pts not able to receive CAPOX-B upon PFS1, PFS2 was considered equal to PFS1. Secondary endpoints were overall survival (OS) and time to second progression (TTP2), which was defined as the time to progression or death on any treatment following PFS1. All endpoints were calculated from the time of randomization. Results: A total of 558 pts were randomized. Median follow-up is 33 months. The median number of maintenance cycles in arm B was 9 (range 1-54). The median PFS1 in arm A vs B was 4.1 vs 7.4 months (HR 0.44, 95% CI 0.37-0.54, p<0.0001). Upon PFS1, 72% of pts received CAPOX-B in arm A and 44% in arm B. The median PFS2 was 10.4 vs 10.4 months (HR 0.86, 95% CI 0.7-1.04, p=0.12). The median TTP2 in arm A vs B was 11.5 vs 15.4 months (HR 0.58, 95% CI 0.48-0.72, p<0.0001), and the median OS was 17.9 vs 21.7 months (HR 0.77, 95% CI 0.62-0.96, p=0.02), respectively. Conclusions: Maintenance treatment with capecitabine plus bevacizumab after 6 cycles CAPOX-B did not significantly prolong PFS2, which may be due to the lower number of pts in arm B that received CAPOX-B following PFS1. Maintenance treatment significantly prolonged PFS1, TTP2 and OS. Our data support the use of bevacizumab plus capecitabine until progression or unacceptable toxicity. Updated results will be presented. Clinical trial information: NCT00442637.

Gene expression profiles of circulating tumor cells in metastatic breast cancer patients

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Background: A circulating tumor cell (CTC) count is an established prognostic factor in metastatic breast cancer. Besides enumeration, CTC characterization promises to further improve outcome prediction and treatment guidance. We have previously shown the feasibility of measuring the expression of a panel of 96 clinically relevant genes in CTCs in a leukocyte background, and in the current study, we determined the prognostic value of CTC gene expression profiling in metastatic breast cancer. Methods: CTCs were isolated and enumerated from blood of 130 metastatic breast cancer patients prior to start of first-line systemic, endocrine or chemotherapeutic, therapy. Of these, 103 were evaluable for mRNA gene expression levels measured by quantitative RT-PCR in relation to time to treatment switch (TTS). Separate prognostic CTC gene profiles were generated by leave-one-out cross validation for all patients and for patients with ≥5 CTCs per 7.5 mL blood, and cut-offs were chosen to ensure optimal prediction of patients who might benefit from an early therapy switch. Results: In the total cohort, of whom 56% received chemotherapeutic and 44% endocrine therapy, baseline CTC count (≥5 versus <5 CTCs/7.5 mL blood) predicted for TTS (Hazard Ratio (HR) 2.92 [95% Confidence Interval (CI) 1.71 – 4.95] P <0.0001). A 16-gene CTC profile for all patients and a separate 9-gene CTC profile applicable for patients with ≥5 CTCs were identified, which distinguished those patients with TTS or death within 9 months from those with a more favorable outcome. Test performance for both profiles was favorable; the 16-gene profile had 90% sensitivity, 38% specificity, 50% positive predictive value (PPV) and 85% negative predictive value (NPV), and the 9-gene profile performed slightly better at 92% sensitivity, 52% specificity, 66% PPV and 87% NPV. In multivariate Cox regression analysis, the 16-gene profile was the only factor independently associated with TTS (HR 3.15 [95%CI 1.35 – 7.33] P 0.008). Conclusions: Two CTC gene expression profiles were discovered, which provide prognostic value in metastatic breast cancer patients. This study further underscores the potential of molecular characterization of CTCs.

Dextromethorphan As a Phenotyping Test to Predict Endoxifen Exposure in Patients on Tamoxifen Treatment

Purpose

Tamoxifen, a widely used agent for the prevention and treatment of breast cancer, is mainly metabolized by CYP2D6 and CYP3A to form its most abundant active metabolite, endoxifen. Interpatient variability in toxicity and efficacy of tamoxifen is substantial. Contradictory results on the value of CYP2D6 genotyping to reduce the variable efficacy have been reported. In this pharmacokinetic study, we investigated the value of dextromethorphan, a known probe drug for both CYP2D6 and CYP3A enzymatic activity, as a potential phenotyping probe for tamoxifen pharmacokinetics.

Methods

In this prospective study, 40 women using tamoxifen for invasive breast cancer received a single dose of dextromethorphan 2 hours after tamoxifen intake. Dextromethorphan, tamoxifen, and their respective metabolites were quantified. Exposure parameters of all compounds were estimated, log transformed, and subsequently correlated.

Results

A strong and highly significant correlation (r = −0.72; P < .001) was found between the exposures of dextromethorphan (0 to 6 hours) and endoxifen (0 to 24 hours). Also, the area under the plasma concentration–time curve of dextromethorphan (0 to 6 hours) and daily trough endoxifen concentration was strongly correlated (r = −0.70; P < .001). In a single patient using the potent CYP2D6 inhibitor paroxetine, the low endoxifen concentration was accurately predicted by dextromethorphan exposure.

Conclusion

Dextromethorphan exposure after a single administration adequately predicted endoxifen exposure in individual patients with breast cancer taking tamoxifen. This test could contribute to the personalization and optimization of tamoxifen treatment, but it needs additional validation and simplification before being applicable in future dosing strategies.

Trastuzumab beyond progression: overall survival analysis of the GBG 26/BIG 3-05 phase III study in HER2-positive breast cancer

BACKGROUND

Continuation of trastuzumab plus capecitabine (XH) showed a significantly improved overall response rate and time to progression compared with capecitabine (X) alone in women with HER2-positive breast cancer progressing during trastuzumab treatment. Here, we report the final analysis on overall survival.

PATIENTS AND METHODS

Patients with HER2-positive, advanced breast cancer who progressed during treatment with trastuzumab with or without 1st-line metastatic chemotherapy were prospectively randomised to X (2500mg/m(2) on days 1-14, q3w) or XH (6 (8)mg/kg, q3w). Overall survival was a pre-specified secondary end-point.

RESULTS

Median follow-up at June 2010 was 20.7months. Fifty nine of 74 and 60 of 77 patients died in the X and XH arm, respectively. Median overall survival was 20.6 and 24.9months with X and XH, respectively (HR=0.94 [0.65-1.35]; p=0.73). Performance status and metastatic site were independent prognosticators for overall survival. No difference between treatment arms was observed for patients who achieved clinical response or clinical benefit, respectively. Patients who continued/restarted anti-HER2 treatment (trastuzumab or lapatinib) after 2nd progression (N=52) had a post-progression survival of 18.8 compared with 13.3months for those who did not receive 3rd line treatment with anti-HER2 agents (N=88) (HR 0.63; p=0.02).

CONCLUSIONS

Final overall survival analysis of the GBG-26 study did not demonstrate a significant survival benefit for treatment beyond progression with trastuzumab. However, in a post-hoc analysis, patients receiving anti-HER2 treatment as 3rd line therapy showed a better post-progression survival than those not receiving this targeted treatment.

mRNA and microRNA expression profiles in circulating tumor cells and primary tumors of metastatic breast cancer patients

PURPOSE

Molecular characterization of circulating tumor cells (CTC) holds great promise. Unfortunately, routinely isolated CTC fractions currently still contain contaminating leukocytes, which makes CTC-specific molecular characterization extremely challenging. In this study, we determined mRNA and microRNA (miRNA) expression of potentially CTC-specific genes that are considered to be clinically relevant in breast cancer.

EXPERIMENTAL DESIGN

CTCs were isolated with the epithelial cell adhesion molecule-based CellSearch Profile Kit. Selected genes were measured by real-time reverse transcriptase PCR in CTCs of 50 metastatic breast cancer patients collected before starting first-line systemic therapy in blood from 53 healthy blood donors (HBD) and in primary tumors of 8 of the patients. The molecular profiles were associated with CTC counts and clinical parameters and compared with the profiles generated from the corresponding primary tumors.

RESULTS

We identified 55 mRNAs and 10 miRNAs more abundantly expressed in samples from 32 patients with at least 5 CTCs in 7.5 mL of blood compared with samples from 9 patients without detectable CTCs and HBDs. Clustering analysis resulted in 4 different patient clusters characterized by 5 distinct gene clusters. Twice the number of patients from cluster 2 to 4 had developed both visceral and nonvisceral metastases. Comparing transcript levels in CTCs with those measured in corresponding primary tumors showed clinically relevant discrepancies in estrogen receptor and HER2 levels.

CONCLUSIONS

Our study shows that molecular profiling of low numbers of CTCs in a high background of leukocytes is feasible and shows promise for further studies on the clinical relevance of molecular characterization of CTCs.

The addition of pravastatin to chemotherapy in advanced gastric carcinoma: a randomised phase II trial

PURPOSE

Statins have for long been considered to play a potential role in anticancer treatment based upon their ability to inhibit the mevalonate synthesis pathway. This randomised phase II trial compared the efficacy and safety of pravastatin added to epirubicin, cisplatin and capecitabine (ECC versus ECC+P) in patients with advanced gastric carcinoma.

METHODS

Patients were randomised to receive up to six cycles of 3-weekly ECC with or without pravastatin (40 mg, once daily from day 1 of the first cycle until day 21 of the last cycle). Primary end-point was progression-free rate at 6 months (PFR(6 months)). Secondary end-points were response rate (RR), progression-free survival (PFS), overall survival (OS) and safety. For early termination in case of futility, a two-stage design was applied (P(0) = 50%; P(1) = 70%; α = 0.05; β = 0.10).

RESULTS

Thirty patients were enrolled. PFR(6 months) was 6/14 patients (42.8%) in the ECC+P arm, and 7/15 patients (46.7%) in the control arm, and therefore the study was terminated after the first stage. In the ECC and ECC+P arm, RR was 7/15 (46.7%) and 5/15 (33.3%), median PFS was 5 and 6 months and median OS was 6 and 8 months, respectively. Toxicity data showed no significant differences, although there was a trend towards more gastrointestinal side-effects such as diarrhoea and stomatitis in the ECC+P arm.

CONCLUSION

In this randomised phase II trial the addition of pravastatin to ECC did not improve outcome in patients with advanced gastric cancer. Therefore, further testing of this combination in a randomised phase III trial cannot be recommended.

Trastuzumab beyond progression in human epidermal growth factor receptor 2-positive advanced breast cancer: a german breast group 26/breast international group 03-05 study

PURPOSE

Trastuzumab shows clinical activity in human epidermal growth factor receptor 2 (HER-2)-positive early and advanced breast cancer. In the German Breast Group 26/Breast International Group 03-05 trial, we investigated if trastuzumab treatment should be continued beyond progression.

METHODS

Patients with HER-2-positive breast cancer that progresses during treatment with trastuzumab were randomly assigned to receive capecitabine (2,500 mg/m(2) body-surface area on days 1 through 14 [1,250 mg/m(2) semi-daily]) alone or with continuation of trastuzumab (6 mg/kg body weight) in 3-week cycles. The primary end point was time to progression.

RESULTS

We randomly assigned 78 patients to capecitabine and 78 patients to capecitabine plus trastuzumab. Sixty-five events and 38 deaths in the capecitabine group and 62 events and 33 deaths in the capecitabine-plus-trastuzumab group occurred during 15.6 months of follow-up. Median times to progression were 5.6 months in the capecitabine group and 8.2 months in the capecitabine-plus-trastuzumab group with an unadjusted hazard ratio of 0.69 (95% CI, 0.48 to 0.97; two-sided log-rank P = .0338). Overall survival rates were 20.4 months (95% CI, 17.8 to 24.7) in the capecitabine group and 25.5 months (95% CI, 19.0 to 30.7) in the capecitabine-plus-trastuzumab group (P = .257). Overall response rates were 27.0% with capecitabine and 48.1% with capecitabine plus trastuzumab (odds ratio, 2.50; P = .0115). Continuation of trastuzumab beyond progression was not associated with increased toxicity.

CONCLUSION

Continuation of trastuzumab plus capecitabine showed a significant improvement in overall response and time to progression compared with capecitabine alone in women with HER-2-positive breast cancer who experienced progression during trastuzumab treatment.

[Lower costs for anticancer drugs by safety margin around calculated dose and by fine-tuning on ampoule strength]

OBJECTIVE

To determine if the rational application of dose individualization of anticancer drugs leads to a reduction in costs.

DESIGN

Data analysis.

METHOD

At the Ikazia Hospital in Rotterdam, the Netherlands, over the first 19 weeks of 2006 the costs of the intravenous administration to patients of one or more anticancer drugs were determined. The costs of dosage based on body surface area (BSA) were calculated. Commercially available ampoule strengths were not taken into consideration. Using available pharmacokinetic data, it is reasonable to assume that a deviation of up to 10% based on an individualized dose calculated by body surface area, has a negligible effect on the outcome of treatment. For this reason drug costs by rounding off doses to whole ampoules were also investigated. A condition of this was that the rounded-off dose should not deviate by more than 10% from the dose calculated on body surface area.

RESULTS

During the study period, 18 different anticancer drugs were administered a total of 939 times. If dosage had been based strictly on body surface area, drug costs would have been euro 509,664. Rounding off to whole ampoules with a dose margin of a maximum of 10% would have cost euro 465,619: a reduction in cost of 8.6%.

CONCLUSION

The rational application of the dose individualization principle based on body surface area may result in a substantial reduction in expenditure on anticancer drugs.

Evaluation of an Alternate Dosing Strategy for Cisplatin in Patients With Extreme Body Surface Area Values

Purpose

The majority of cytotoxic drugs for adults are dosed based on body surface area (BSA), aiming to reduce interpatient variability in drug exposure. We prospectively studied the usefulness of BSA-based dosing of cisplatin in patients at extremes of BSA values.

Patients and Methods

Patients were randomly assigned to receive a fixed dose of cisplatin in course 1, and a BSA-adjusted dose in course 2, or vice versa. The fixed dose was based on the average BSA for males and females, while extremes were set at BSA values exceeding the average ± 1 standard deviation. Subsequently, we retrospectively analyzed data from a normal population.

Results

In 25 patients assessable for both courses, the use of a fixed dose of cisplatin resulted in reduced exposure to unbound platinum in patients at the upper extremes of BSA (P = .003) and higher exposures in patients at the lower extremes (P = .009), as compared with exposures following the BSA-adjusted dose. Although clearance was related to BSA (R2 = 0.44; P < .001), only a small reduction in interpatient variability in clearance after correction for BSA was achieved (20.8% v 17.1%). In the retrospective analysis, compared with the average patient, the clearance of unbound platinum in patients with a BSA value ≤ 1.65 m2 was 16% slower (P < .001), while an 18% faster clearance (P < .001) was observed in patients with a BSA value ≥ 2.05 m2.

Conclusion

Unless better predictors for platinum clearance are identified, fixed-dose regimens per BSA cluster (≤ 1.65 m2; 1.66 m2 to 2.04 m2; ≥ 2.05 m2) are recommended.

Population pharmacokinetics of cisplatin in adult cancer patients

PURPOSE

To characterize the pharmacokinetics of the anticancer agent cisplatin, and explore the influence of patient covariates and interoccasion variability on drug disposition.

METHODS

Data were obtained from 285 patients (519 complete curves; 3483 plasma samples) who received the drug as a 3-h intravenous infusion at a mean dose of 144 mg (range 75-210 mg). The population model was built with the use of NONMEM, performing generalized-additive modeling to identify candidate covariates including body-surface area (BSA), age, sex, height, weight, hematocrit, total protein, albumin, serum creatinine, and creatinine clearance, and using a backward deletion protocol to obtain the final models for clearance (CL) and volume of distribution (V).

RESULTS

The final model was a one-compartment linear model with BSA (in meters squared) as the only significant covariate that impacted on both CL and V: TVCL (in liters per hour)=51.7+26.3x(BSA-1.855) and TVV (in liters)=41.1+24.6x(BSA-1.855), where TVCL and TVV are referred to as typical values that could be used a priori in dosage regimen design. The interindividual and interoccasion variability estimates for CL and V were 16.82 and 20.35%, and 13.93 and 22.91%, respectively.

CONCLUSION

A population pharmacokinetic model for cisplatin has been developed that incorporates measures of body size to predict clearance. In this patient population, cisplatin pharmacokinetics were not associated with age, sex, or measures of renal dysfunction.